1. Field of the Invention
The invention relates to shock mounting electronic devices. In particular, the invention relates to shock mounting an imaging device used in an endoscopic video camera.
2. Description of the Prior Art
Charged coupled device (CCD) video cameras have come into extensive use in industrial and medical fields. In medical applications these cameras attach to an eyepiece of an optical instrument called an endoscope so that one or more physicians observe on a television monitor what one formerly viewed directly by eye at the endoscope eyepiece. With a diameter of generally less than 10 mm, endoscopes are passed into body cavities through small holes to observe structures and perform procedures previously requiring large surgical openings. Two of the most common types of CCD cameras that are in use in medical surgery today are the single CCD camera and the 3-CCD camera, the latter sometimes called a 3-chip camera. In the case of the 3-CCD camera, light entering the camera from a lens system is separated by a multi-part glass prism assembly, whose optical faces are coated with high and low pass dichroic coatings, such that red light wavelengths of the incoming light image are reflected to one CCD, the blue wavelengths from the image are reflected to a second CCD, and the green wavelengths pass through to a third CCD. The three primary color images from the three CCD's are then recombined to form one color image. The recombined color image has greater line resolution than a comparable single CCD medical camera, and superior color reproduction. The high resolution, superior color video image produced by the 3-CCD camera is favored by some surgeons for use in medical procedures. The negative side of the 3-CCD camera is that it is larger, heavier, more expensive than a single CCD camera, and the adhesively assembled glass prism and CCD assembly is relatively easily damaged by rough handling. Further, the recombination of the three primary color images must be done with extreme accuracy to obtain the improved image resolution. Any displacement or breakage of components in the assembly due to shock or thermal distortion severely reduces image resolution or eliminates it entirely, and is virtually unrepairable.
Prior U.S. patent application Ser. No. 09/252,330, filed Feb. 18, 1999 and entitled Shock Mounting System for CCD Camera, assigned to the assignee hereof and incorporated by reference herein, shows one way of shock mounting a CCD camera. The disclosure in that application involved securing support plates to the prism assembly (to join the components together) and then enclosing the support plates in an elastomeric preformed boot structure interposed between the support plates and the camera housing. It has been found that the invention disclosed herein is an improvement over the devices and methods disclosed in this prior application.
It is accordingly an object of this invention to produce a system to reinforce and mount a camera assembly to enable it to withstand inadvertent shock loads.
It is another object of this invention to produce a system and method to shock mount a 3-CCD camera assembly to enable it to withstand shock loads such as a drop from a surgical table to a hard floor that would normally destroy an unmodified 3-CCD camera.
It is a further object of this invention to produce a system for converting a 3-CCD camera from non-ruggedized form to a ruggedized form.
It is another object of this invention to produce a shock mounting system for a 3-CCD camera that is relatively easy to manufacture and repair.